I would like to know what size tires are on that crown. I think they are a wide base tire maybe 385/65r22.5 or 425/65r22.5 ( 14.9 or 16.6 wide) A true super single should not be mounted on that rim. Super singles (455/55r22.5 or 445/50r22.5 ) are some where around 17.5 inches wide and they don't look that wide.

... Today I saw a trailer with super singles with a flat, getting a new tire installed on the side of the road. ...

First time I saw a super single, I was going to the VW parts place (a major trauma in itself) and had to park down the street because a t-trailer making a delivery had a flat on a s-s and was broken down blocking the whole parking lot. Not a good way to get a positive impression the first time! (I need 'em on MY bus like your gramma needs track spikes ...)

Does/did anyone make higher speed rated heavy truck tires? Like in a 11RX24.5 with a very high speed rating? Curious minds wonder. My old Crown Supercoach would top out at around 85mph at 2150rpm in 10th gear. Some of our older American Lafrance fire apparatus would easily do 80+. Old old Engine 2 comes to mind. (1975) A long time ago. Some of the newer stuff will go over 90+. HB of CJ (old coot)

If someone driving one of our buses or any large vehicle for that matter goes the speeds you suggest, I'm thinking tire speed ratings will mean little or nothing to them.

At those speeds a maximum braking effort will result in a stopping distance likely well in excess of 500 feet. Hell, my Corvette Z06 is capable of 195 MPH speeds and it actually has tires rated for those speeds. I have managed in the 6 years I owned it to get it up to 85. I'm not worried about my equipment, it is the idiots on the highway that are out to get me. In a bus we are far more likely to have the inability to stop be the issue than the speed rating of tires.

The highest rated speed for on road truck/bus tires is 75mph. If you go over-run 10psi higher and expect lower tread life. Personally-I firmly believe all trucks and buses should have a built in, non changeable governor at 65mph. 75mph or faster is just plainly a 10-25ton missile going down the road that can't stop worth a bean. Disc brakes are a bit better, but still too fast. Good Luck, TomC

You need to be aware that the wheel bearings / hubs are designed for the load to be on the large inner bearing, the smaller outter bearing is only to hold the assy on the large bearing. Correct when they offset the wheel assy out, your sure gonna have bearing issues, no surprise there.

Don't all DOT rated tires have at least the 18% safety factor for speed and load meaning a tire can run or carry a load for short periods of time @ 18 % over the stamped rating on the sidewall I know Toyo uses 20 %

It sounds as though you are saying it is OK to exceed rated speeds by 18% because that is the built in margin. So at 88.5 MPH nothing bad will happen, but if you go to 18.5% or 88.875 MPH the tire disintegrates? Are you suggesting manufacturing tolerances are so well controlled any speed up to 18% higher than the rating is OK because the manufacturers derate the tires just to be consistent with one another?

People hang on your advice here. To have you even suggest all limits such as tire speed ratings are advisory only encourages those who think buses are OK at high speeds can be dangerous. I agree with Tom C. Completely.

Regarding those who are not content with the limitations they are test pilots.

I may be the slowest XLII driver, but whenever we travel at our 62 MPH speed we are passed by others as if our engine had quit. But ironically those drivers that have gone by us at high rates of speed usually go by us multiple times during the day. Maybe they are hurrying to the next bathroom.